Hi Tobias,
The only file you need to replace is jboss-remoting.jar, which lives in $JBOSS_HOME/client and $JBOSS_HOME/server/$CONFIG/lib. Also, the remoting classes are in $JBOSS_HOME/client/jbossall-client.jar, so you should either put jboss-remoting.jar in front of jbossall-client.jar on your client's classpath, or rebuild jbossall-client.jar with the new remoting classes.
-Ron